Air conditioning apparatus including condensate preventing means



W. AIR CONDITIONING APPARATUS INCLUDING May 28, 1968 1.. MO GRATH CONDENSATE PREVENTING MEANS Filed Feb. 25. 1966 FIG.2

FlG.l

INVENTOR.

MC GRATH. WZ W WILLIAM L.

ATTORNEY.

United States Patent 3,385,350 AIR CONDITIQNING APPARATUS INCLUDING C(BNDENSATE PREVENTING MEANS William L. McGrath, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Feb. 25, 1966, Ser. No. 530,208 4 Claims. (Cl. 16539) ABSTRACT OF THE DISCLOSURE Air conditioning apparatus such as a fan coil unit provided with condensate preventing means when the fan is shut-down. The fan energization circuit includes a switch which permits operation of the fan at low speed and a temperature responsive switch actuator which reflects temperature within the unit to operate the fan to prevent condensate formation within the housing when cold, moist air contacts the housing or fan scroll.

This invention relates to an air conditioning apparatus, and, more particularly, to an arrangement for controlling condensate formation in an air conditioning apparatus.

In air conditioning apparatuses of the type employing a heat exchange coil arranged to circulate a heat exchange medium therethrongh, for example chilled water, and having a fan for bringing air to be conditioned into heat exchange relation with the coil, condensate may form and accumulate within the apparatus, if the heat exchange medium continues to flow when the fan is shut off. Condensate accumulating within the air conditioning apparatus can fall onto the floor underneath the apparatus making the installation unsightly, and possibly staining or damaging the floor or floor covering.

It is the principal object of the present invention to provide a new and improved air conditioning apparatus.

It is a further object of the present invention to provide a control arrangement for an air conditioning apparatus effective, at the occurrence of a predetermined condition Within the apparatus conducive to the formation of condensate, to operate the apparatus air circulating fan to sustain circulation of condensate inhibiting air through the apparatus.

It is a further object of the present invention to provide an air conditioning apparatus incorporating automatic means to prevent formation and accumulation of condensate within the apparatus housing following shutdown of the air conditioning apparatus.

This invention relates to an air conditioning apparatus comprising in combination an enclosure; a heat exchange coil in the enclosure within which a heat absorbent medium is adapted to flow; a fan for circulating air to be conditioned through the enclosure into heat exchange relation with the coil; an energizing circuit for the fan; a first switch eiiective when moved to complete the fan energizing circuit so that upon flow of the heat absorbent medium through the coil the apparatus cools; and means for preventing formation of condensate in the enclosure following shutdown of the fan, the condensate preventing means including a second switch adapted when actuated to complete the fan energizing circuit bypassing the first switch whereby condensate inhibiting air is circulated through the enclosure by the fan, and a temperature responsive actuator for the second switch adapted at a predetermined temperature condition within the enclosure to actuate the second switch.

Other objects and advantages will be perceived from the ensuing description and drawings in which:

FIGURE 1 is a plan view of an air conditioning apparatus incorporating the improved condensate preventing means of the present invention; and

3,385,350 Patented May 28, 1968 FIGURE 2 is a wiring diagram illustrating the control arrangement for the air conditioning apparatus shown in FIGURE 1.

Referring to FIGURE 1 of the drawings, an air conditioning apparatus 10 is therein shown which includes heat exchanger coil 12 housed within a generally rectangular enclosure or housing 14. A suitable heat exchange medium, for example, chilled Water, may be circulated through coil 12. Valve 18 in inlet line 19 regulates the flow of heat exchange medium to coil 12.

Coil 12 is arranged across the outlet of fan scroll 20. Fan 22, having drive motor 24, is adapted to draw air to be conditioned through inlet 26 into the lower region of housing 14 and discharge the air across coil 12. Conditioned air from coil 12 passes through louvered outlet 28 in the upper side of housing 14 into the area being conditioned, for example a room. Filter 29, disposed across inlet 26, filters the incoming air.

Referring to FIGURE 2 of the drawings, winding 32 of fan motor 24 is connected between contact 36 of control switch 35 and power lead L Control switch arm 38 is connected to power lead L Leads L and L are connected to a suitable source of alternating current power (not shown). It is understood that a three-phase source of alternating current power may be used if the circuit is suitably modified.

Winding 32 of fan motor 24 is tapped at 39 to provide a low speed winding part 33. Winding tap 39 is connected to contact 37 of control switch 35.

Control switch arm 38, when moved to close contact 37, completes an energizing circuit to winding part 33 of motor 24. Motor 24 drives fan 22 at reduced speed. When moved to close contact 36, control switch arm 38 completes an energizing circuit to the whole winding 32 of motor 24 and motor 24 drives fan 22 at full speed.

A temperature responsive bimetallic switch 40, physically attached to a metal part which is susceptible to sweating such as on the lower portion of fan scroll 20, and arranged to close at a predetermined temperature condition, is connected across control switch contact 37 and lead L Closure of switch 40 completes an energizing circuit to winding part 33 of motor 24 and fan 22 is driven at reduced speed.

For operation of the air conditioning apparatus 10, valve 18 is opened, permitting the heat exchange medium, i.e., chilled water, to fiow through coil 12 and control switch arm 38 is set to close contact 36 or 37 so that motor 24 drives fan 22 at either full or reduced speed.

When switch 35 is opened to stop fan motor 24, condensate may form within enclosure 14. The tendency of condensate to form within enclosure '14 of air conditioning apparatus 10' is pronounced when shut-off valve 18 is open and the relatively cold heat exchange medium, i.e. chilled water, flows through coil 1C chilling the air thereabout. In the absence of air fiow through enclosure 14 due to the stopping of fan 22, the chilled air gravitates to the lower regions of enclosure 14 cooling the sheet metal parts, i.e. fan scroll 20, of the air conditioning apparatus. Where relatively warm humid outdoor air, either from seepage or through opening of window 45, contacts the relatively cool par-ts of the air conditioning apparatus, large amounts of condensate may form and collect thereon, particularly on the lower portions of fan scroll 20.

Condensate formed within the air conditioning apparatus can fall onto the floor which, in addition to being unsightly, may stain and damage the floor. Additionally, the condensate could possibly rust the sheet metal parts of the air conditioning apparatus.

Bimetal switch 40, arranged in heat exchange relation with a part of the air conditioning unit 10 prone to form and accumulate condensate, for example, the lower part of fan scroll '20, is arranged to close at a temperature condition at which condensate is most likely to occur. Closure of switch 40 completes an energizing circuit to winding part 33 of motor 24 to operate fan 22 at a reduced speed to sustain circulation of air through enclosure 14 and prevent accumulation of chilled air within the contines of enclosure 14.

*Bimetal switch 40 may be arranged to energize motor winding 32 of motor 24 so that motor 24 drives fan 22 at full speed.

It is understood that a thermostat may be employed to move arm 38 of control switch 35 to close and open contacts 36, 37 thereof and thereby control both operation and speed of fan 22 in response to temperature condition of the area being conditioned. In that construction, the control arrangement of the present invention serves to bypass the thermostat and complete an energizing circuit to winding part 33 of motor 24 to operate fan 22 at reduced speed to prevent accumulation of condensate within the apparatus during the thermostat oif cycle.

While I have described a preferred embodiment of this invention, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

T claim:

1. In an air conditioning apparatus, the combination of an enclosure; a heat exchange coil in said enclosure within which a heat absorbent medium is adapted to flow; a fan in said enclosure to pass air to be conditioned through said enclosure into heat exchange relation with said coil; a prime mover to drive said fan, an energizing circuit connected to said prime mover; a "first switch effective to complete said prime mover energizing circuit to actuate said fan to pass air through said coil in heat exchange relation with heat absorbent medium therein to cool said air; and means for preventing formation of condensate in said enclosure following deenergization of said prime mover thereby discontinuing operation of said fan, said condensate preventing means including a second switch adapted when actuated to complete said prime mover energizing circuit bypassing said first switch whereby said prime mover is actuated to drive said fan to draw condensate inhibiting air in said enclosure over condensate collecting elements of said apparatus, and a temperature responsive actuator to actuate said second switch at a predetermined temperature condition within said enclosure.

2. An air conditioning apparatus according to claim 1 in which said temperature responsive control switch actuator is arranged in intimate heat exchange relation with a part of said apparatus below said heat exchange coil.

6. An air conditioning apparatus according to claim 2 in which said fan is disposed below said heat exchange coil, said fan having a housing, said temperature responsive control switch actuator being in intimate heat exchange relation with a part of said fan housing.

4. An air conditioning apparatus according to claim 1 in which said energizing circuit includes a first circuit effective when completed to actuate the prime mover to operate said fan at a first relatively low speed and a second circuit effective when completed to actuate the prime mover to operate said fan at a second relatively high speed; said second switch being adapted when actuated to complete said first circuit.

References Cited UNITED STATES PATENTS 4/1940 Hoesel 62-89 5/1949 Seifner et al 16539 X 

